Sylvite flotation from potassium-containing crude salts



Int. Cl. B03d 1/02 US. Cl. 209-166 2 Claims ABSTRACT OF THE DISCLOSURE Process for recovering sylvite by flotation from potassium-containing crude salts, wherein alkyl-diamines containing 7 to 22 carbon atoms are used as collectors.

It is known from French Patent 1,429,888 and German Patent 1,043,233 that linear primary monoamines having a chain length of 8 to 22 carbon atoms are suitable as flotation reagents for the froth flotation of potassiumcontaining crude salts. Linear diamines of the general formula in which R represents an alkyl radical having from 8 to 22 carbon atoms and n represents an integer from 2 to 4 on the other hand, have no collector action for sylvite.

In contradistinction thereto, we have found that, surprisingly, diamines of the general formula I in which R and R represent saturated or unsaturated, straight-chain or branched alkyl radicals, containing together 7 to 22 carbon atoms, and in which the symbol n. represents an integer from 2 to 4, possess an excellent collector action for sylvite especially in brines having a high magnesium content. Among these diamines of the Formula I, those are preferably used as collectors which contain as one of the radicals R and R, a methyl or ethyl group.

The superior collector action of the diamines of the present invention in the flotation of potassium-containing crude salts over the hitherto used monoamines is especially marked when using the diamines for brines which contain more than 3% by weight of magnesium ions. Such brines are obtained during the separation of sylvite by flotation from decomposed carnallite, since they are in most cases floated up from the decomposition brine.

Thus, the object of the present invention is a process for recovering sylvite by flotation from potassium-containing crude salts, especially from magnesium-containing brines, wherein diamines of the Formula I in which n represents an integer from 2 to 4, and R and R represent saturated or unsaturated, straight chain or branched alkyl radicals containing together about 7 to 22 carbon atoms, or mixtures thereof, are used as collectors.

The diamines used as collectors in the recovery of nited States Patent ice sylvite by flotation may be prepared according to known methods. They can be obtained, for example, from corresponding monoamines, for example, by adding onto these acrylonitrile and subsequently hydrogenating them or also by reacting these with ethyleneimine, propyleneimine or butyleneimine. The monoamines used as starting substances can be prepared in known manner by the reaction of a-olefines with hydrocyanic acid according to Ritters reaction (German Patent 870,856 and I. Am. Oil Chemists Soc., 41, 78-81 (1964)), furthermore by hydrogenation of nitro-paraflins, by hydrogenation of asymmetrical ketones in the presence of ammonia and by the reaction of chloroalkanes with ammonia. Depending on the method of preparation used, the secondary amino group of the diamines of the present invention may be linked to a determined carbon atom of the alkyl chain or it may be distributed satistically over the whole chain. The products of the present invention may constitute bodies that have pure chains or mixtures of chains.

In contradistinction to the hitherto used reagents the diamines of the present invention are liquid substances and exhibit, therefore, many advantages with regard to their manipulation. They may be used in their free form or in the form of their salts. For neutralization, which may be effected stoichiometrically or with a larger or smaller amount, there is especially suitable hydrochloric acid or acetic acid. The optimum degree of neutralization depends on the type of the crude salt used.

The quantity of diamine to be used for the flotation depends on the accompanying minerals of the crude salt as well as on the sylvite content. In general, it is in the range of 20' to 200 g. per ton of crude salt.

The flotation operation to recover sylvite from patassium-containing crude salts, using the diamines of the present invention as collectors, may be carried out according to known processes, for example according to the processes described in the monograph Potash and Potassium Fertilizers by Robert Noyes, Noyes Development Corporation, Park Ridge, N.J., USA. (1966), pages 80 to 82 and '84 to 88. During flotation, there may also be used in known manner so-called frothers for improving the flotation effect and, if necessary, for modifying the froth. As such frothers, there may be mentioned, for example, cresols and xylenols (cresylic acids) and primary or secondary aliphatic and alicyclic alcohols containing about 4 to 10 carbon atoms, such as pentanols, hexanols, and especially methyl isobutyl carbinol (MIBC), and furthermore polyalkylene glycols having molecular weights of up to about 600. Under polyalkylene glycols, there are to be understood in the present case compounds resulting from the addition of alkylene oxides to aliphatic alcohols as block polymers such, for example, as polypropylene glycol, onto which the ethylene oxide had been added.

So-called depressants which prevent the flotation concentrate from enriching 'with slime components may also be used simultaneously. Such known depressants are described, for example, on page 102 of the above-mentioned monograph by Robert Noyes. The depressants essentially consist of colloidal substances such as cellulose ether, starch, guar flour, glue, polyacryloamides, and similar substances.

For the flotation according to the present invention, even other flotation auxiliary agents may be added, for example, hydrocarbon oils (fuel oil, gas oil, kerosene) or other auxiliary agents.

The advantageous effect of the diamines used according to the present invention for the flotation of potassiumcontaining crude salts does not only set in when the mentioned diamines or mixtures of these diamines are used alone as collectors, but these advantageous effects can also be observed when the diamines are used together with 3 4 the monoamines hitherto employed as collectors. When EXAMPLE 2 V such mixtures of diamines and monoarnines are used, the Samples of a crude Salt having the following mean proportion of the diamines in the mixture should amount composition; to at least 30 percent by Weight. Page, The following examples illustrate the invention but they 5 c 28 are not intended to limit it thereto. The percentages ine 60 dicated in these examples are percentages by Weight. Mgcl2 7 EXAMPLE 1 MgSO 2 In tests to demonstrate the recovery eificiency of vari- Insoluble matte! 3 ous collectors, samples of a pulp prepared from 100 g. 10 were deslimed by treating them four times with a brine. of sylvite and 0.5 l. of brine were conditioned for 3 min- The samples of the crude salt treated in this manner were utes with the amines indicated in the following Table 1 then subjected, as described in Example 1, to flotation, in form of their hydrochlorides and subsequently subwith the addition of amines and diamines. jected to flotation in a laboratory flotation cell. The brine The brine had the following composition: had a specific gravity of 1.294 and the following com- G /1 position: 82.8 1 16.6 Mg 97.8 133 K 2 8 250.2 Na 3.7 Cl 305.6 The amines were added in quantities of each time 100 S0 0-6 g. per ton of sylvite. In addition, 60 g. of pine oil and The amine collectors were added in quantities of 50, 10 g. of starch per ton of sylvite were added. The col- 75 and 100 g. respectively, of amine per ton of sylvite, lectors employed and the recoveries of the flotation operain form of aqueous solutions having a strength of 2%. tions are listed in Table 2.

TABLE 2 Feed concentrate, percent Recovery Tail, percent of K20 in Collector R By weight K20 content percent By weight K10 content Stearylamjne, RNHg 10 25. 4 90 14. 7 Oleylamine, RNH 3 4o 7. 7 97 17. 0 Tallow [at amine, R- 12 48 32. 5 88 13.5 Diamine On, 24 57 72.2 70 5.3

R-CHz-CH I HN--(CH2)3NH2 I Diamine C11 26 58 85.2 74 3.6

R [JH,-OH

HN( 0 H2) :NH;

Diamine 011-015 23 54 70.3 77 6.7

R(]HCHz-OH HN(CH2)5NH2 TABLE 1 The fatty amines used for comparison had the following I chain distribution: Recov'ery H1 6115611 11 on adgl010f gOf 45 00 8C 01' 8-1 Collzzetpr ton of syl ito 0 C" Cm 018" 1'8. 6 1H Collector R percent 100 75 g gglg g 4 g Stcarylamine, aw 1 gut-gm 13 1 3 50 Tallowfatamine 24 45 iziii'i i n fa jfi ffi .f'. .I oi? 100 95 o 70 R-([JH-CH:

NH(CH2)3NH2 The above Tables 1 and 2 clearly show that the col- Diaminc C15 100 98 90 78 lectors of the present invention have a far better eliect RCHOHa than the known collectors. The action of the fatty amines JHPCHEMNHZ can be considerably improved when they are combined I C 100 8 93 "6 with the diamines of the present invention. Very surfi i t f 'm w 9 prising is the very good recovery of potassium chloride T H NH with simultaneous excellent selectivity, which brings about LEI-(C 2 0 the high K 0 contents in the flotation concentrates. stemylamine, RNHz m-Crs 30 90 35 75 We claim: fi g fil'fi 4D 1. Process for recovering sylvite by froth flotation from I IH(CH2)aNH2 potassium-containing crude salts, comprising utilizing as a collector at least one compound of the formula Stearylamine, RNHZ Clo-ice 59 96 9 74 5 Diamine Ora-C20 5U RCHCH3 R OH. R'

l NI I(OHQ)=NHQ HN-(CHz)nNH2 Stearylamine, RNH 94 87 fi ea' eng 70 in which n represents an integer from 2 to 4, and R and R represent saturated or unsaturated, straight chain or branched alkyl radicals containing together 7 to 22 carbon fi j mo 91 78 65 atoms; and (II) 0-70% by weight of a primary alkyl- I amine having 8-22 carbon atoms; and separating the NH-(CH2)2NHZ sylvite from the froth.

5 6 2. Process as claimed in claim 1, wherein the collectors 2,166,150 7/1939 Mowk 209166 X are used in a quantity of from 20 to 200 g./ton crude 2,329,149 9/1943 Weiner 209-166 salt. OTHER REFERENCES Chem. Abstracts, vol. 54, 1960.

References Cited UNITED STATES PATENTS 3,260,365 7/ 1966 Dickson 209166 HARRY B. THORNTON, Primary Examiner 3,404,777 10/1968 Ray et a1 209166 

